Weakens the mouth of the case.
Flare as much as you need to allow bullet to set on case prior to seating....and keep rollin'!
Beveling 9mm and Other Pistol Cases
- Thread starter DMW1116
- Start date
Weakens the mouth of the case.
Flare as much as you need to allow bullet to set on case prior to seating....and keep rollin'!
FROGO207
Member
I have never deberred or chamfered an auto type brass handgun casing that I remember in 30+ years. I just expand the mouth enough using the appropriate plug.
Revolver brass or rifle brass that I have trimmed or am inserting flat based bullets in I do indeed chamfer and debur.
Revolver brass or rifle brass that I have trimmed or am inserting flat based bullets in I do indeed chamfer and debur.
One thing about chamfering and beveling. Sometimes too much can leave a knife edge on the case mouth and if you are as clumbsy as I am, you can get painful cuts when handling (I once failed to get my finger out of the way when sizing a 38 Special freshly sized and chamfered case. I was on a roll and on about the 80th case cut a nice 35 caliber half circle out of the side of my index finger. Perhps a "dull" case mouth wouldn't hve cut easy enough to cut?). I put chamfering/deburring in the "if you wanna, go for it. If you don'y wanna, don't" file.
I’m not doing anything like that. I do about 1-1.5 turns of the Lyman chamfering tool. The bevel created is less than 1/64” wide.
Since we’re in this topic and two pages in, I normally only really need to deburr if I’ve trimmed cases. If I went through the trouble to trim 9mm cases like I do revolver cases, would it make any difference in accuracy? One of my 9mm pistols shoots the 147 gr RMR Heavy Match Winner very well. I rarely trim 9mm brass but if it would make a difference I may well start when loading for that pistol.
Since we’re in this topic and two pages in, I normally only really need to deburr if I’ve trimmed cases. If I went through the trouble to trim 9mm cases like I do revolver cases, would it make any difference in accuracy? One of my 9mm pistols shoots the 147 gr RMR Heavy Match Winner very well. I rarely trim 9mm brass but if it would make a difference I may well start when loading for that pistol.
This is what I do. If you don't, even with new revolver brass it will shave the lead or the coating even with an expanded mouth.
243winxb
Member
Handgun brass
Starline Brass has suggested deburring case mouth when its to hard to get the Dillon powder funnel, expander out of the case.
I say, fix the expander, leave brass alone.
After trimming, then chamfer and deburr. Lightly. The "M" expander works well.
Starline Brass has suggested deburring case mouth when its to hard to get the Dillon powder funnel, expander out of the case.
I say, fix the expander, leave brass alone.
After trimming, then chamfer and deburr. Lightly. The "M" expander works well.
Lafitte
Member
Beveling the edge of the case leaves a sharp edge on the case mouth. Since auto pistols head space on the front edge of the case I like a good flat edge on the case. If anything, I just lightly de-burr the inside of the case.
Lafitte
Lafitte
Fine Figure of a Man
Member
I have never loaded 9mm on anything other than a progressive press. I can usually feel a cracked case in the resizing die and discard it before it is primed. This would be the most intimate moment I share with a piece of 9mm brass.
For auto cases, one should do just enough to remove any burr and just barely knock off the sharp 90 degree "point", no more. If the case is sharp now, it's way over done, even 1/64th is big in the 9MM de-burring world.
IWAC
Member
For the greatest crimp consistency, I trim my cases, then deburr the interior, and the exterior if there is a burr that will catch my fingernail. The seating die will not iron it out. A lot of people never trim their cases, and I wonder about their accuracy. If/when the cases grow a significant amount, I do it again.
A little explanation...My calibers are .38 Spl./357 Magnum.. straight wall, rimmed cases. They are a different animal from 9mm, and need different care. Sorry if I caused confusion.
A little explanation...My calibers are .38 Spl./357 Magnum.. straight wall, rimmed cases. They are a different animal from 9mm, and need different care. Sorry if I caused confusion.
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armoredman
Member
I've been loading cast in 9mm for some years now and I have never beveled the case mouths. I do expand slightly more than I would for jacketed, but never bevel. No issues so far. I also size them down to .356, not .358.
This.
I chamfer the inside of the case mouth if I am loading cast bullets. It takes the edge off the case, reduces the chance of shaving the bullet, and allows me to minimize my flare.
With semi-auto cases, which I almost never trim, it is a one time thing.
As Walkalong said, you can chamfer too much if you are not careful.
AJC1
Member
Because 9mm headspaces on the rim so it very well could. No difference than sorting 22 by rim thickness. Depends on your level of ocd. I dont....
AJC1
Member
I don't find any measurable growth in straightwall cases or my process would include that step. I trim all my revolver brass once and I've not seen more than .002 growth ever. If I did I'd uniform them again. Most auto cases are short and never reach trim lengrh.
Charlie98
Member
It's really a matter of diminishing returns, as I stated previously. If all you are loading is 9mm practice ammos for your carry piece, for example, you are gaining nothing by the tedium of trimming up something like 1000 9mm cases.
Granted, if you are blowing it out for a target pistol... then by all means.
Its like you know. I’m getting ready to buy a 22 rim thickness gage. I’ll have to try some 9mm trimmed vs untrimmed and see I suppose.
LiveLife
Member
This is so true, especially for small internal case volume 9mm.
Most reloaders don't realize case length shortens as brass is reloaded repeatedly due to carbide resizing ring not reducing all the way down to case base (Only roll-sizing/push through resizing reduces case base OD as frequently posted by @jmorris
And you can't push through resize 9mm due to tapered case). So overtime, even untrimmed brass can be short enough to headspace less and less off case mouth to chamber (Eventually, headspacing off extractor) to leak more and more gas when powder is ignited.Keep in mind, chamber pressure won't build sufficiently until case mouth/neck expands enough to seal with chamber - So anything done to not help this like making case shorter won't help with pressure build/max consistency.
There are many reloading variables which will affect chamber pressure build and average max pressures that in turn will influence accuracy on target (Group size and scatter).
While trimming 9mm brass can improve flare/taper crimp consistency, any improvement WILL BE overshadowed by mixed range brass with varying case wall thickness to affect neck tension/finished OAL/bullet setback (Why we don't trim 9mm brass and focus on consistency of other reloading variables). We already know bullet seating depth variance of a few thousands (Whether from finished OAL or from chambered bullet setback) can vary chamber pressures by several thousand PSI - https://www.thehighroad.org/index.p...-and-discussions.778197/page-11#post-12503881
+1
So if you want to improve accuracy, start with reloading variables that will overshadow other variables first. For me, I would prioritize by following:
- Sorted brass by same headstamp that produces least amount of finished OAL variance (Use longer resized case length for less gas leakage) - https://www.thehighroad.org/index.p...r-oal-consistency.911743/page-5#post-12455241
- Headstamp brass that produces no bullet setback - https://www.thehighroad.org/index.p...neck-tension-and-bullet-setback.830072/page-4
- Use of minimal amount of taper crimp (Or none, just to return flare back flat on bullet) to not reduce OD of bullet ... That's usually adding .022" (As typical case wall thickness at case mouth is .011") to the diameter of bullet
- Longer vs shorter OAL that will produce smaller groups for a given powder charge
- Powder burn rate for specific charge (start/low vs mid/near max load data) that will produce smaller groups from efficiency of powder burn that affects chamber pressure build/max averages
But go ahead and show us how trimming and beveling 9mm brass can improve accuracy (But be warned of THR peanut gallery that will shout "testing methodology and sample size"
)Note that you want maximum case wall thickness at case mouth (Part that will expand the first/most) to seal with chamber wall to build pressure and sufficient neck tension around the bullet base as expressed by even bulging around the bullet base to prevent bullet setback and more consistent chamber pressures - https://www.thehighroad.org/index.p...-and-discussions.778197/page-10#post-11419509
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jmorris
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I have (re)loaded hundreds of thousands of 9mm rounds and have trimmed exactly zero of them.
GeoDudeFlorida
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Rule #2: If it works for you, then it works. Period. End of story.But go ahead and show us how trimming and beveling 9mm brass can improve accuracy (But be warned of THR peanut gallery that will shout "testing methodology and sample size"
Note that you want maximum case wall thickness at case mouth (Part that will expand the first/most) to seal with chamber wall to build pressure and sufficient neck tension around the bullet base as expressed by even bulging around the bullet base to prevent bullet setback and more consistent chamber pressures - https://www.thehighroad.org/index.p...-and-discussions.778197/page-10#post-11419509
lordpaxman
Member
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- Jun 4, 2011
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9mm headspaces on the mouth. But I’m with you on not trimming 9mm - after prettying it up by wet tumbling the only thing I want to do is reload and shoot.
GeoDudeFlorida
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My normal routine with 9mm is to tumble in plain, untreated cob to get the grunge out and remove primer residue. Then they get a hand inspection. I’m specifically looking for bulging, bent rims, cracks, primer crimps, non-brass material, ejector dings and torn rims from extraction. Then they get decapped and the primer pockets checked, then they get tumbled in treated walnut.
I see a lot of these issues in varying degrees - from no-fix-needed to complete repurpose of the case. I toss very few, mostly plated steel.
I know a lot of folks won’t bother fixing 9mm cases but I do, especially if it’s minor damage. I also repurpose a fair amount to 9mmMak. That’s just me. If I come across burrs or uneven mouths I will trim it up and deburr. I feel about profile and dimensions like some folks do about shiny.
